It is generally known that a number of fuel cells are joined together to form a fuel cell stack. Such a stack generally provides electrical current in response to electrochemically converting hydrogen and oxygen into water and energy. The electrical current is used to provide power for various electrical devices in a vehicle or in other suitable mechanisms. Each fuel cell generally includes a proton exchange membrane (PEM) (or membrane) positioned between an anode catalyst and a cathode catalyst. A membrane electrode assembly (MEA) generally includes the membrane, the anode catalyst, the cathode catalyst and a pair of gas diffusion layers (GDLs) (one positioned on the anode side proximate to the membrane and another positioned on the cathode side proximate to the membrane). A first flow field plate that defines a plurality of channels is positioned on the anode side of the fuel cell. A second flow field plate that defines a plurality of channels is positioned on the cathode side of the fuel cell. During fuel cell stack startups, shutdowns, and soaks (i.e., non operation of the fuel cell), oxygen may be present on the cathode side of the PEM in which higher catalyst erosion due to oxygen diffusion through the MEA may be observed.
Degradation may be higher when fresh air enters into a cathode side of the fuel cell stack and diffuses through the MEA to the anode side creating an air/fuel boundary. For example, it has been found that at the air/fuel boundary developed at the anode side after a fuel cell shut down or during fuel cell restart may cause a quick degradation of the anode catalyst. The thickness, the catalyst active surface area, and therefore the performance of the anode catalyst layer may be reduced due to the presence of oxygen on the cathode side when the fuel cell is not operational and diffuses to the anode side where hydrogen is present.